The invention relates to a structure of an electromagnetic solenoid valve used to introduce air into a negatively pressurizing path of, e.g., an actuator of an electrically driven suction pump.
FIG. 3 is a plan view showing a structure of an exemplary conventional electromagnetic solenoid valve of this type; and FIG. 4 is a front sectional view showing the electromagnetic solenoid valve shown in FIG. 3.
In FIGS. 3 and 4, a coil assembly 1 is made up of a coil bobbin 1a, a coil 1b wound on the coil bobbin 1a, a terminal outlet 1c of the coil 1b and a terminal 1d. Reference numeral 2 designates a core inserted into the coil bobbin 1a; 3, a plunger vertically reciprocating within the coil bobbin 1a while confronting the core 2; 4, 5, plates serving as magnetic flux paths; and 6, a spring for biasing the plunger.
The operation of the above conventional electromagnetic solenoid valve will now be described. Upon application of a line voltage to the terminal 1d, the coil 1b wound around the coil bobbin 1a is energized and generates a magnetic field, thereby exciting the plunger 3. The excited plunger 3 is attracted to the core 2 while resisting the biasing force of the spring 6.
Upon interruption of the application of the line voltage to the terminal 1d, the plunger 3 is returned to its original position by the biasing force of the spring 6.
In the conventional electromagnetic solenoid valve thus constructed, the coil assembly 1 and the plate 4 are fixed only by an adhesive or the like as shown in FIG. 3, but are not provided with a rotation stopper. Thus, should the adhesive fixation between the coil assembly 1 and the plate 4 be destroyed during the operation of the electromagnetic solenoid valve, the electromagnetic solenoid valve including the coil assembly 1 which would be free to rotate, may shortcircuit between the terminal 1d of the coil assembly 1 and the plate 4, thereby preventing current across the coil 1b of the coil assembly 1, flow and potentially making the plunger 3 inoperative.
The present invention has been made in view of the problems mentioned above. Accordingly, an objective of the invention is to provide an electromagnetic solenoid valve constructed such that a terminal of coil and a plate serving as a magnetic path will not be shortcircuited.